Efforts to free a five-year-old boy from a gunman in an underground bunker, where he fled after killing the boy's school bus driver, were shrouded in secrecy on Saturday as the standoff in rural Alabama dragged into a fifth straight day.

Police sources said the FBI's Hostage Rescue Team, often described as federal law enforcement's only full-time counterterrorism unit, was leading negotiations aimed at securing the boy's safe release.

But FBI officials have declined to comment, referring calls to local authorities who have have been extremely tight-lipped, providing few official updates on the situation.

Dale County sheriff Wally Olson, chief spokesman for local law enforcement officials in Midland City, told a brief news conference on Saturday that authorities had been "in constant communication" with the suspect, who was officially identified on Friday as 65-year-old Jimmy Lee Dykes.

A retired trucker and Vietnam veteran, Dykes is the man police believe responsible for killing bus driver Charles Albert Poland, 66, on Tuesday and then taking one of Poland's child passengers hostage as they rode home from school.

The incident came against the backdrop of a debate about gun control that has galvanized the nation since the shooting deaths of 20 children and seven adults at a Connecticut elementary school in December.

Olson declined to diclose any specific demands made by Dykes, saying only that he had allowed the authorities to provide coloring books, toys and medication for the kindergarten-age boy.

Dykes also assured the authorities that he had blankets and electric heaters in the bunker to protect the boy from cold overnight temperatures, Olson said."I want to thank him for taking care of our child. This is very important," Olson said.

He offered no further comment but one law enforcement source, explaining perhaps why so little information is being shared with reporters, told Reuters that Dykes has access to television news inside his bunker.

According to his neighbors, Dykes moved into the Midland City area about two years ago and was often seen patrolling his property at night with a gun and a flashlight.

He kept mostly to himself and had spent a lot of time building the subterranean bunker near the trailer where he lived, several neighbors have told reporters.

Ronda Wilbur, a neighbor who has described Dykes as a "mean man" who beat one of her dogs to death with a lead pipe, said she thought he had been planning something for a long time.

"I had always figured he was more or less a wacko survivalist, but it's obvious that this had been very well thought out and arranged," Wilbur told a local ABC television news affiliate.

Dykes had been scheduled to appear for a bench trial on Wednesday after his arrest last month on a menacing charge involving one of his neighbors.